Named Briney Eccentric Bore tooling, a new end mill holder design is said to reduce the TIR that is typical of end mill holders using a set screw or Weldon flat set screw by as much as 75 percent. According to the company, the out-of-concentric condition of the toolholder bore is improved from 0.0008" to 0.0002", and the holders feature an eccentric bore, imparting 0.0003" eccentricity in the direction of the set screw. The company-developed internal grinding process was designed to impart the feature consistently to any of Briney’s end mill holders, regardless of size, without affecting other toolholder features and tolerances.
By incorporating the eccentric bore, the clearances between the toolholder bore and the cutting tool can reduce the runout condition when the cutting tool is secured in the bore and rotated during cutting operations. What potentially results is an improvement in cutting performance because the runout of the assembled tool and holder is reduced, says the company.
For example, a standard 1" toolholder bore diameter is 1.0001," and the end mill for that holder is 0.9997." In addition, the clearance between the diameters is 0.0004." With the 0.0003" eccentric bore, as the set screw is tightened, the clearance is pushed to within 0.0001" of the center, while the standard holder maintains the 0.0004" clearance and the clearances are pushed 0.0004" off-center. When a set screw is turned down into the standard holder and the tool is rotated 180 degrees, the total runout is 0.0008."
Related Content
-
Best Practices: Machining Difficult Materials
Cutting hardened steel, titanium and other difficult materials requires picking the right tools, eliminating spindle runout and relying on best practices to achieve tight part tolerances.
-
Choosing Your Carbide Grade: A Guide
Without an international standard for designating carbide grades or application ranges, users must rely on relative judgments and background knowledge for success.
-
How to Turn Machine Shop Downtime Into Process Expertise
To take advantage of a lull in business, JR Machine devised a week-long cutting tool event that elevated the shop’s capabilities with aerospace alloys.